Lubricating system for air motors



Nov. 20, 1951 E. H. SHA1-'F 2,575,640

LUBRICATING SYSTEM FOR AIR MOTORS Filed Nov. a, 1947 I vue est CHL Sh o.

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Patented Nov.y20, 1951 LUBRICATING SYSTEM FOR AIR MOTORS Ernest H.Shaft, Spring Lake,`Mich., assignor to Keller Tool Company, Grand Haven,Mich., a

corporation of Michigan Application November 8, 1ML-Serial No. 784,873

The present invention `pertains to pneumatic tools and more particularlyto tools embodying .rotary vane type air motors.

.An important object of Vthe invention is to .provide for effectivelubrication of the various working parts of a tool of the abovecharacter through the utilization of air under pressure delivered to alubricant Areservoir when the tool is in opera tion Aand serving toforce lubricant from the reservoir to the Ytool parts upon interruptionof the air supply.

.A further object is to provide such a tool which is extremely compact,highly efficient in operation and inexpensive to manufacture.

Other objects and advantages of the invention will become apparent fromthe following detailed description of the preferred embodimentillustrated in the accompanying drawings in which:

Figure 1 is a perspective view of A a portable grinder constructed inaccordance with the present invention.

Fig. 2 is a central longitudinal section of the tool shown in Fig. 1taken inthe plane substantially perpendicular to the control valvetherein.

Fig. 3 'is a transverse section taken substantially in the plane of line3-3 in Fig. 2.

While the invention is susceptible of various modifications andalternative constructions, there is shown in the drawings and willherein be de- Y the spirit and scope of the invention as expressed l inthe appended claims.

As illustrated in the drawings, the exemplary form of the invention isshown embodied in a portable pneumatic grinder which includes a generally cylindrical casing I2 having therein a motor chamber It withinwhich is an air motor i6 for actuating the tool. The motor I3 is of thevane type `and comprises a cylinder i8 having an eccentrically disposedbore I3 therein, and a rotor 24 eccentrically disposed within the boreI9, and ends of the cylinder being closed by end plates 28 and 22. Therotor 24 is provided with equally spaced slidable vanes for cooperationwith the wall of the bore I 9 and is mounted on a central spindle 26extending through the end plates 2G and 22' and supported in bearings 28and 29.

As shown, the spindle 26 is enlarged intermediate its ends to provide ashoulder 3i! against which the lower bearing 29 is held by means of anut 3| screw-threaded on the spindle. The

s claims. (c1. 121-34) vouter race of the bearing 29 is received vin arecess `provided therefor in a retaining ring 32 screw-#threaded iin theforward end of the casing I2 and holding the race against the motor endplate 22. To receive the upper bearing 28 the -rear -end plate 20 is ofcup shape. Thus ithas .a rearwardly projecting ange 2| formingxA a,recess into which A'the outer race of the bearing is fitted. The bearingis clamped between `the [casing I2 Vand the 'end plate '20 by the`revtaining ring 32 acting through the forward end plate 22 and thecylinder I8.

The spindle`26 extends through 'the ring 32, beyond the casing I2, andadjacent the outer end thereof, it is fashioned into a split sleeve 33having a tapered en'd portion '34, which tof'- gether with a nut 35forms fa collet-"chuck for the reception of a tool'3I.` A l Pressure`fluid, such as compressed air, to actuate the motor'IG is supplied tothe tool from AVany suitable source (not shown) by way of e.

ffitting 31 received in a bore 38 `in the rearY end -of `the casing |2.From thefbore 38 air passes through a longitudinal passage 39 toajcontrol valve 40. The valve 40 includes a bushingl'l closely fitted ina transverse bore 42 vin the casing I2. is a spring 'biased valveplunger 43 having a portion 43a, which is adapted to seat against theinner end of the bushing 4|. One end of the plunger Y43 extends 4beyondthe :casing I2 (Fig. l) for 'engagement by a lever 44 positioned foractuation by the vfinger of an operator.

From the valve 40, air passes through a port 45 in the l'bushing '4|into a transverse passage 46 and by way of apassage 41 into an annularinlet distribution channel or passage '48 formed by a rabbet groove inthe iiange 2| of the rear end plate 20 in cooperation with the outerrace of the bearing 28 and the casing I2. From the inlet channel 48 airis delivered Ato the motor cylinder I4 through aport 49 inthe endplaten.

Spent air is exhausted from the motor it through slots 50 in the wall ofthe cylinder I8 'into an exhaust chamber 5| defined by the outer suriaceof the cylinder coacting with the inner wall of the motor chamber lli,and through exhaust ports V52 in the casing I2 to the atmosphere.

To lubricate the tool I provide means including Ya lubricant reservoirand a system of interconnecting passages to which air under pressure issupplied when the tool is running and which is operative upon stoppingthe tool to supply lubricant thereto. More specifically, I provide alubricant reservoir in the casing I'2 with con- Shiftable axially withinthe *bushing 4l necting passages through which air under pressure issupplied when the valve 4D is opened, and upon interruption of the airsupply, incident to the closure of the valve 46, lubricant, such aslight oil, is forced from the reservoir to the rotor chamber I9 and tochambers adjacent the bearings 28 and 29. Additionally, I provide ametering device or restriction to prevent 'escape of lubricant from thereservoir upon equalization of pressure on opposite sides of therestriction.

As shown, adjacent the rear bearing 28 the bottom of the casing l2 iscounterbored, and toging passages 56 therein. :'In the present instance,the lubricant reservoir :is in the form of a generally rectangularchamber 60 adjacent the rear end of the casing I2 which is closed bymeans of a plug 6l closely fitted in a bore 62 in the wall of the casingl2. The

plug 6l has a filling opening therethrough which is adapted to be closedby a screw and washer 63 and 64, respectively.

" Air under pressure is supplied to the reservoir `6l) when the valve 48is opened to admit air to actuatev the motor by means of a passage 65extending therefrom longitudinally of the casing |2 and having one endopening into the annular inlet channel 4R. Intermediate its ends. thepassage 65 is intersected by the transverse passage 46. As previouslyset forth; the inner end of the latter serves as an air inlet passage;however, it is interrupted by the valve bushing 4|, and thus admissionof air under pressure to the lubricant reservoir 60 is solely by way ofthe inlet channel 48.

In the present instance, restriction of communication between thelubricant reservoir 60 and the motor I6 is accomplished by a cylindricalplug 66 positioned within and adjacent the outer end of the passage 46.The plug 66 is retained in the passage by means of a second plug 61closelv fitted in the end of the passage 46 and having its outer endpeened into engagement with the wall of the casing I2` The plug 66 is ofslightly smaller diameter than that of the passage 46 thus providing aspace between the two. It has been found that an effective difference ofthese two diameters is on the order of .001 of an inch. Thus air underpressure can enter the reservoir 60 from the inlet channel 48 by way ofthe passage 65 around the plug 66. and a. small quantity lubricant willbe forced out of the reservoir reversely along the same route until thev.pressure on both sides of the plug is equalized. Upon suchequalization of the pressure, the plug 66 provides sufficientrestriction to prevent leakage. While in the illustrative embodiment theplug 66 is shown to be of a diameter to provide aspace between it andthe wall of the passage 46, va. porous plug such as one of sinteredmetal fitted in the passage 46 can be used instead.

Lubricant delivered to the inlet channel 48 is conducted into the motorcylinder I8 to lubricate the wall of the bore i9 and the rotor 24 andits'ylvancs.v n f,

Lubricant is supplied to the bearing chamber 53 by means of a passage 68extending therefrom and connecting with the passage 46 adjacent the plug66. Thus, when air supply is interrupted incident to the closing of thevalve 40, lubricant will be delivered to the chamber 53 as well as tothe channel 48.

summarizing, air under pressure is delivered to the tool by way of thevalve 46, port 45, passages 46 and 4l to t-he inlet channel 48 andthence into the cylinder I6 through port 49 to drive the motor. Alsofrom the channel 48 air under pressure is delivered to the lubricantreservoir 60 through the passage 65 around the plug 66 in the passage46. When the valve 4l) is closed, interrupting the supply of pressureair, some lubricant is forced from the reservoir 6! until the pressureon both sides of the plug 66 is equalized, such lubricant beingconducted to the channel 48 by way of the passage 65 and to the chamber53 where it lubricates the bearing 28 by way/cf the passage. 68. Fromthe channel 43 lubricant is delivered into the cylinder through the port49, and from' the chamber 63 lubricant is deliveredto the chamber 54through the passages 55 and 56 to lubricate the bearing 29.

From the foregoing, it can be seen that I have provided a highly eicientand extremely compact tool having relatively few parts with a consequentsaving in manufacturing costs. Further, effective lubrication of thetool is provided through the provision of a closed lubricant reservoirto which air under pressure is supplied when the tool is in operationand which has communication with lubricant chambers provided for each ofthe spindle bearings and the rotor chainber, lubricant being deliveredfrom the reservoir to the chambers as an incident to the interruption ofthe air supply to the tool, provision being made to prevent lubricantfrom escaping from the chamber upon equalization of pressure thereinwith that outside.

I claim as my invention:

1. A rotary pneumatic tool comprising, in combination, an elongatedcasing having a chamber in one end and a closed lubricant reservoir atthe other end, a motor in said chamber comprising a cylinder and endplates at the forward and rear ends thereof, said cylinder coacting withthe inner wall of the motor chamber to form an exhaust chamber, aspindle extending through the cylinder end plates axially thereof, arotor mounted on said spindle and eccentrically dis.- posed within saidcylinder and having varies slid.- ably engaging the inner cylinder wall,a bearing for the rear end of the spindle comprising an outer racecarried by the rear end plate and an inner race on the spindle, abearing for the forward end of the spindle comprising an outer racemounted in the casing and an inner race fast on the spindle, and meansfor supplying air under pressure to the motor chamber. and lubricantreservoir comprising a'yalve controlled air passage and an annular inletchannel, the outer race of the rear bearing coasting with the end plateand with said casing to form said channel, inlet ports connecting saidchannel to said motor and a restricted passage connecting said channelto said reservoir, a rear lubricant chamber formed by said casing andthe rear spindle bearing and in restricted communication with saidlubricant reservoir and a second lubricant chamber formed by the forwardend plate and ,75 bearing, said spindle having a duct connecting saidbearing chambers so that lubricant is conducted from said reservoir tosaid motor and bearing chambers by reason of pressure built up in thereservoir under operating conditions.

2. A rotary pneumatic tool comprising, in combination, an elongatedcasing having a chamber in one end and a closed lubricant reservoir atthe other end, a motor in said chamber including a spindle, a rotormounted on the spindle and a bearing rotatably supporting said spindle,and means for supplying air under pressure to the motor chamber andlubricant reservoir, said means including a valve-controlled air passageand an annular inlet channel, longitudinally disposed inlet portsconnecting said channel with said motor chamber and providing restrictedcommunication with said reservoir, and a lubricant chamber for saidbearing in concentric relation with said channel and also in restrictedcommunication with said reservoir whereby lubricant is conducted fromsaid reservoir to said motor and bearing chambers by reason of pressurebuilt up in the reservoir under operating conditions.

3. A rotary pneumatic tool comprising, in combination, a elongatedcasing having a chamber in one end and a closed lubricant reservoir atthe other end, a motor in said chamber including a spindle, a rotormounted on the spindle and a bearing rotatably supporting said spindle,

and means for supplying air under pressure to the motor chamber andlubricant reservoir, said means including a valve-controlled air supplypassage and a distribution passage communieating with said air supplypassage and in restricted communication with said reservoir, and alubricant chamber for said bearing also having restricted communicationwith said reservoir whereby lubricant is conducted from said reservoirto said motor and bearing chambers by reason of pressure built up in thereservoir under operating conditions.

ERNEST H. SHAFF.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 967,693 Weinland Aug. 16, 1910994,400 Holt June 6, 1911 1,809,141 Mock June 9, 1931 1,878,747Youngblood Sept. 20, 1932 1,947,430 De Mooy Feb. 13, 1934 1,956,644Hamerly May 1, 1934 2,099,280 Shaff Nov. 16, 1937 2,111,583 De Mooy Mar.22, 1938 2,238,101 Cliiord Apr. 15, 1941 2,384,872 Baker et al Sept. 18,1945 2,407,613 Mannet al Sept. 10, 1946

